In recent times, gaseous and liquid bulk goods, such as gases and oil, are transported to an ever increasing extent using pipelines, often over considerable distances. It is clear that the laying of pipelines along the bottom of the sea as well as in mountainous terrain under very different climatic conditions imposes stringent requirements upon the weathering and corrosion resistance of the protective coatings applied to the pipes.
With unprotected metallic pipes, damage occurs as early as during the laying operation. This leads to rusting through of the pipes due to corrosion after only a brief period of time. Therefore, paints and especially also coating powders have been developed in recent years in an attempt to achieve excellent surface protection (cf., for example, DOS No. 2,507,786). In a number of cases, it is desirable or even necessary to apply a concrete casing to powder-coated pipes. This is the case, for instance, if the pipe is to obtain the weight necessary for submarine laying or if the pipe is to be additionally protected. Moreover, it may also be expedient to bond the pipe firmly to concrete for reasons of a safe laying installation. However, the use of concrete presents the obstacle of poor adhesion to the powder-coated pipe surface. Furthermore, when using powder-coated construction steel materials, a positive bond is required between concrete and the reinforcing steel materials. Such a bond can be realized only unsatisfactorily by special shaping of the steel components.
Processes involving adhesive promotion between concrete and synthetic resin surfaces have been known. Basically, these are applied to the bond between concrete and powder-coated articles. Thus, for example, Japanese Laid-Open Application No. 53 041 020 describes the use of silane primers for improving adhesion of concrete to a urethane resin coat. However, these processes have the disadvantage that the desired improvement in adhesion requires an additional working step.
A bond can also be established between metallic surfaces and concrete by means of vinyl acetate resins containing cement powder. Although adhesion is achieved in this case, corrosion protection is not ensured.